Nonwoven fabrics are composed of fibers which may be consolidated by purely mechanical means such as, for example, entanglement caused by needle-punching, by chemical means such as, for example, saturation with a polymeric binder, or by combinations thereof. Some nonwoven fabrics are used at temperatures substantially higher than ambient temperature such as, for example, glass fiber-containing nonwoven fabrics which are impregnated with a hot asphaltic composition pursuant to making roofing shingles or roll roofing material. When a nonwoven fabric is contacted with a hot asphaltic composition at temperatures of 150.degree.-250.degree. C., the nonwoven fabric may sag, shrink, or otherwise become distorted. Therefore, nonwoven fabrics which incorporate a polymeric binder should substantially retain the properties contributed by the polymeric binder such as, for example, strength. In addition, the binder should not substantially detract from essential nonwoven fabric characteristics, as would be the case, for example, if the polymeric binder were too rigid or brittle or became sticky under processing conditions.
There is a need for a method for making a heat-resistant nonwoven fabric by using heat-resistant fibers and a heat-resistant nonwoven polymeric binder composition which is free of potentially polluting solvents and is also free from formaldehyde.